Mooring can be very expensive, and in the Med moorings can be difficult to find. Moorings generally get cheaper the further east you move in the Med. Spain's mooring prices are in my experience comparable to high cost UK Marinas. While in France its very much depends on where you can get a mooring as the prices vary considerably. Our mooring in France is extremely reasonable compared to the UK, but I am told there is a waiting list for years for a mooring in this location. If you are willing to moor in unusual locations; for instance rivers, then you might be able to secure a bargain somewhere. It depends on what you find acceptable. Marina life is not for everyone, but is safer and more secure than some of the other options.
Commutability to the location, the cultural stimulation the location has to offer, mobility once at the destination and the friendliness of the locals are all factors one needs to consider. Yacht Chandlers in the Med are expensive, more so than in the UK. Getting work done can be expensive too. In Spain for instance they are very protectionist over their yachting industry. You might not even be allowed to work on your own vessel in some Spanish yards, this is to encourage the employment of locals. Additionally, it prevents the thriving expat community from getting a foothold in the marine maintenance market. There are always exceptions to the rule, but I mention it so as to highlight the fact that homework needs to be done on the subject; before you arrive at a Spanish port hoping to carry out your standard yearly maintenance program.
Everything that I have mentioned here is based on my own experience. It is very much my opinion on the given subject.
I will add to these notes when I can.